Amino-thiophanthraquinones



Reissued July 10, 1951 AMINO-THIOPHANTHRAQUINON ES Henry R. Lee and Viktor Weinmayr, Pitman, N. J

assignors to E. I. du Pont de Nemours & Company, Wilmington, Del., a corporation of Delaware No Drawing. Original N 0. 2,501,132, dated March 21, 1950, Serial No. 723,672, January 22, 1947. Application for reissue February 9, 1951, Serial 4 Claims.

Matter enclosed in heavy brackets l' appears in the original patent but forms no part of this reissue specification; matter printed in italics indicates the additions made by reissue.

This invention relates to new thiophanthraquinones, and more particularl to the preparation of amino-substituted thiophanthraquinones of the formula:

wherein any one of the positions 5, 6, 7 and 8 carry an amino group, while the remaining positions are unsubstituted.

The term thiophanthraquinone is employed in the naming of this compound in view of the original name used by Scholl and Seer in Ann. 394, 131 (1912), who designated the corresponding unsubstituted hydrocarbon compound thiophanthracene.

It is an object of this invention to prepare new amino-thiophanthraquinones which are useful as starting materials for the preparation of other compounds, and particularly as intermediates for the synthesis of dyes. A further object of the invention is to provide a commercially feasible process for the preparation of these new aminothiophanthraquinones.

The amino-thiophanthraquinones of this invention may be produced by reducing the corresponding nitro-(Z-thenoyl) -o-benzoic acids more particularly disclosed in co-pending application Serial No. 723,670, new Patent N0. 2,513,573, and

then efiecting ring closure of the thenoy1-o-- benzoic acid group, or they may be produced by reducing the nitro-thiophanthraquinones more particularly described in co-pending application Serial No. 723,671, now Patent No.-2,501,131,

either after they have been isolated, or Without isolation from the ring closure mass in which they have been formed. The nitro-(Z-thenoyl) o-benzoic acids, as disclosed in the co-pending application above mentioned, may be prepared by reacting the nitro-substituted phthalic anhydrides with the Grignard reagent prepared from '2-bromothiophene or 2-iodothiophene, or by condensation of the corresponding nitrophthalic anhydride with thiophene by the aid of aluminum chloride or similar condensing agent. These nitro-(Z-thenoyl)-o-benzoic acids may then be reduced to the corresponding amino derivatives, as hereinafter described.

The following examples are given to illustrate the invention. The parts used are by weight,

2 Example 1 formula:

N02 6 5 COOH 5 c 0 OH 4 1 co s 3 00 S N 05 were dissolved in 50 parts of 28% ammonia, and this solution was added in 15 minutes to the boiling slurry of ferrous hydroxide prepared as above. The reaction mass was kept at slightly boiling for 15 minutes longer, and then filtered while still hot. The filtrate, which soon deposited darkcolored material although originally clear and light-colored, was evaporated to dryness without any further clarification. Twenty-five (25) parts of a mixture of [ii-amino-(Z-thenoylX-o-benzoic acid] 3-amz'no-(2-thenoyl) -o-beneoic acid and inorganic salts were obtained. This crude product and 10 parts of boric acid were dissolved in parts of sulfuric acid. vThe dull brown solution was heated at C. for 3 minutes, when it changed to a deep red. It was then cooled and poured onto 500 parts of ice. The red precipitate was filtered off, washed acid-free, then washed with a dilute solution of sodium carbonate, again washed with water and dried. 2.6 parts of crude [E-amino-thiophanthraquinone] 8 amino thiophanthraquinone, melting range 220222 0., were obtained, equal to a yield of 62.8% based on [6-nitro- (2-thenoyl) -o-benzoic acid] 3-nitro-(2-thenoyl) --0-benzoic acid. After several crystallizations from about 35 parts of chlorobenzene per part of crude product, it was obtained in the form of dark red crystals melting at 231-232 C. It was soluble in sulfuric acid with a faint yellow color which turned purple upon the addition of a trace of formaldehyde. The maximum light absorption of an acetone olution of [Eu-amino thiophanthraquinone] 8 aminothz'ophanthraquinone was at a wave length of 491 millimicrons. The maximum light absorption of an alpha-aminoanthraquinone was at 469 millimicrons.

Example 2 Ten (11)) partsz of [Ki-nitro-G2-thenoylr-o-bene zoic acid] 3-nitro-(2-thenoa/Z) obenzoic acid, melting range 216-217 C., were dissolved in 300. parts of water containing 6 parts of sodium hydroxide, and 25 parts of sodium hydrosulfite were" then added at 25 C. The temperature rose spontaneously to 45 C., the solutionturned; deep red, and finally light orange. Theexcessofisodium hydrosulfite was destroyed by adding m-nitrobenzene sodium sulfonate. The solution was clarified by filtering it over absorbent carbon, and evaporated to dryness. Fifty" (50 parts ofcrude product containing [6-amino= ('Z-thenoyI) -o-ben"- zoic acid] 3-amino-(2-thenoyl)-o-benzoic acid were obtained.

This crude product was dissolved in 225 parts of95% sulfuric containing 25 partsof'boric' acid and the solution was heated to 125 C. for a-few minutes. It was then poured onto about 800 parts of ice. The red precipitate was filtered off, washed acid-free with water, then washed with dilute. sodium carbonate and again washed with water. andldriedp 3.15 parts. of crude: [-aminothiephanthraquinonezll 8- amino thiophanthraquinone were obtained.

Five (5-)- parts of this. crude. [5.-amino-thio phanthraquinonel 8:- amino thiophanthxaquinone. wen-er dissolved .im2500 parts. oi chlorobenzene. The solution was passed through a column containing alumina, activated by heating at 325 to 350 Cl. A purple colored band colleeted. near thertop of the column. The-.main product formed; a bright red band whichv was separated andSoxhlet extracted with: ethanol. Upon evaporationof the extract 4.9-parts of [5- amino thiophan'thraquinone] 8 amino thaophanthmauinone were obtained,.me1ting. at 228- 230 C. After twocrystallizations-froma 35 parts oi chlorobenzene per part of product v 3 parts of. pure E5 -amino--thiophanthraquinone]. 8'- amino-thiophanthraauinone melting; at- 23-1-2 32 C. were. obtained.

Example 3 One hundred (100) parts of ferrous sullate were dissolved in 660 parts of water and 160 parts-of 28% ammonia-were added at from 85 to- 9W6. A solution of 10 parts of lE3-n-itro t2 thenoyl'=)-o'-b'enzoic acid] fi-aitro-( z-tlienoyll-o benzoie acid; melting range- 1 69-170"C., in 100 parts of 28% ammonia was added to the above slurry of ferroushydroxide at- 85 to 95 C. in aboutminutes. The reaction masswassgentlly boiled for 15 minutes and filtered: while stillchot. The filtrate was. evaporated. to dryness and 56 parts of product containing [3-amina-(2-thenoyla --o=w--benzoi. acid} fi-ami'no-(z -thenoylr-abenzoic 'acz'd'. were obtained Thirty-seven. (:37 parts. of this cmde product and l6pau1tswof boricaeidrweredissolved in 145 parts oil 95 %v sulfuricacidzran'dtheisolutionrwas heatai'at 95 to. 105 6. forf 2-. /hours. A;red dish. blue solution: was: formed; The IEEsaminothiophanthraquinone]; 8:-am"i1t w thiophanthra qainone was" precipitated-by slowry adding: water to: the sultur-ic acid solution while :keepingi. the temperature below (1.. After parts. of water had: been. added; the sulfate: of. the.--E5- amino thiophan-thraquinone]: 8.- amino. thicphanthmquinoae crystallized out. The. charge was: then. diluted. with. a. total of 150wparts of water, The red precipitate. was: filtered: off, Washed and dried.

3.6 parts of crude [Ev-amino-thiophanthrac1uinone] 8-ammo-thiop7rant7iraqaihone melting at 225 C. were obtained; equal-to ayield" of 60% of theory, based on [3-nitro-(2-thenoyl) -o-benzoic acid] 6-nitro-(Z-thenoyl)-o-benzoic acid. Thev crude product was purified by separating it from impurities on a column of activated alumina as described in Example 2. The purified produ'et thusi obtained 'was crystallized from 21 parts of" chlorobenze-ne and melted at 232-233 .C. It was soluble insuifuric acid with a faint yellow color which. turned purple upon the addition of a trace of formaldehyde. The maximum light absorption of. an" acetone solution was at a wave length of? 491 millimicrons.

Example 4 Eight. parts of [It-nitro-(rZz-thenotID-obenzoic acid] G-nitro-{Z-thenoyl) -o"-benzoic acid, melting range 169-170 C., were added at about 25 C. to a solution of 23 parts of aluminum chloride in. parts ofnitrobenzene. 'Ihetemperature was raised; slowly to C. in three hoursand thecharge: was agitated at 125? to C. for 20 hours. It was then poured. into dilute hydrochloric acid and steam distilled to remove the nitrobenzene. The residue was filtered 01f, washed. andheated. in about 5 parts of pyridine to break up some hard lumps. This crude [8-nitro-thiophanthraquinone] 5 -m'trothiophanthraqui'noae was then reduced and vatted at about 70 C. in a solution of 10 parts of. sodium hydroxide and 3.0.parts of sodium hydrosulfitein 400' parts of water; The orangecolored vat was filtered; and thercru'de [8'aminothiophanthraquinone] 5..- amino flriophanthra quinone was precipitated by blowing. air through the. solution, filtered 01f, washed and dried;

The crude product" thus obtained. was purified by dissolving in" chlorobenzene and. separating the impurities on activated alumina asde'scribed in preceding examples. Upon crystallization from chlorobenzene', [8-amino-thio'phanthraquinone] 5 aminothiophant'hraquinone' melting from 232-233 C. was obtained.

Example 5:

Five (5) parts of [5-nitro- 2 thenoy1)'-o-benzoic acid] 4 -n'itro- 2-thenoyD-o-benzoid acid, melting range 149150 C.,. weredissolyed in a solution of 14" partsof anhydrous aluminium chloride" in 80 parts of nitro'benzene; and the solution'was heated at 125 to 130 C. forwab'out 20"hours.. The. reaction mass was poured into dilute hydrochloric acid and steam distilled to remove. the nitrobenzene. The residue was fillter'ed off, Washed acicbfree, slurri'ed' in warm dilute. sodium carbonate. andifiltere'd again.

This. crude [6' nitro-thiophanthraquinone] 7"- nitrothiophanthraquinone,. without having been dried, was. heatedin. 10 parts of pyridine to break up some hard lumps. It was then poured. intoa solution of 4 parts of sodium hydroxide and 15 parts. of sodium hydrosulfite and heated to about 20 C. The: orange-colored vatwas blown with air, and the [6-amino-thiophanthraquinone] 7- amino-thiopiianifhraqainone was. precipitated, filtered elf. washed and dried.

of:- crude [6-amino-thiophanthraquinone] 7-amino-thiophanthraqainone, melting from 265 to 267 C., were obtained, equal to a yield 011- 55.7 based on IE5 -nitro- (Z-thenoyl) -o benzoic acid] 4 nitro (.2 ---then0g Z)' obenzoic acid. It was dissolved in2000 parts of. chlorobenzene and purified on activated. alummaas Example 6 Ten parts of [4-nitro-(2-thenoyl) -o-benzoic acid] S-nitro-(Z-thenoyl)-o-benzoic acid, melting range l89l90 C., were added at about 25 C. to a solution of 28 parts of anhydrous aluminum chloride in 160 parts of nitrobenzene. The solution was heated at 125 to 130 C. for 20 hours. The crude nitro-thiophanthraquinone was isolated and reduced as described in the preceding example for [fi-nitro-thiophanthraquinone] 7 nitro thiophanthraquinone. Four (4) parts of crude amino-thiophanthraquinone melting at 260 C. were obtained, equal to 48.7% of theory. It was dissolved in 3600 parts of chlorobenzene and purified on a column of alumina as described in the preceding examples. After several crystallizations from 90 parts of odichlorobenzene per part of crude product, amino-thiophanthraquinone melting at 269- 270" C. was obtained. It dissolved in sulfuric acid with a faint yellow color which did not change when traces of formaldehyde were added. The maximum light absorption of its acetone solution was at 465 millimicrons. The product produced by the example is a mixture of 6-aminothiophanthr-aquinone and 7 amino thiophanthraquinone.

Example 7 A solution of 3.5 parts of [4-nitro-(2-thenoyl) o-benzoic acid] 5 -nitro-(2-thenoyl)-o-benzoic acid, melting range 189-190 C., and 1.5 parts of boric acid in 35 parts 96% sulfuric acid was heated at 125 to 135 C. for about 30 minutes, and was then poured on ice. The crude nitrothiophanthraquinone which precipitated was filtered and washed acid-free. It was reduced .and yatted by heating it to about 70 C. in a solution of 4 parts of sodium hydroxide and parts of sodium hydrosulflte in parts of water. The crude amino-thiophanthraquinone was precipitated by adding m-nitrobenzene sodium sulfonate to the vat, filtered, washed and dried.

0.85 part of a, mixture of 6- and '7-amino-thiophanthraquinones, melting at from 269-270 C., was obtained.

As illustrated in the above examples, the nitrothiophanthraquinones can be reduced to the amino-thiophanthraquinones in the condensation mass in which they are formed without isolation or purification. So, also, the nitro-(2- thenoyD-o-benzoic acids may be reduced and ring closed without isolation in pure form, or by separation from the organic salts which are produced in the reduction. Various modifications may of course be made in the reduction and ring closure steps, since the above examples, are given merely to illustrate the invention, and not as limitations thereon.

We claim:

1. The mono-amino-thiophanthraquinones of the formula:

REFERENCES CITED The following references are of record in the file of this patent or the original patent:

Steinkopf: Ann. 407, 99, 107, 108 (1944).

Thomas: Anhydrous Aluminum Chloride, pages 512, 540, Reinhold Pub. Co., 1941.

Groggins: Unit Process in Organic Synthesis, page 188, Edition 2, 1938, McGraw-Hill, N. Y.

Groggins: Ind. Eng. Chem., Apr. 1929, vol. 21,

pages 1 and 2. 

